Porcelain jacket crown



Dec. 14, 1954 H. sAccHl PORCELAIN JACKET CROWN Filed Dec. 2, -1948United States Patent O PORCELAIN JACKET CROWN Hector Sacchi, Montevideo,Uruguay Application December 2, 1948, Serial No. 63,194

2 Claims. (Cl. 32-12) This invention relates to an improved process forthe preparation of porcelain jacket crowns and the resulting crowns.

Prior to my invention, all ordinary techniques for the preparation ofporcelain jacket crowns have been based on the principle of thesuccessive melting of porcelain on metallic matrices or dies, while theporcelain is gradually condensed and moulded to desired shape andconsistency, depending on the skill of the dental worker.

In the above technique, a number of available porcelains, with variedcomposition and properties, are used, but the underlying principle isalways the same, there being only differences in details, depending onthe person using the technique.

In the processes known heretofore, the preparation of jacket crownspresents serious disadvantages; they are troublesome, too slow, and theresults are not always positive as regards shape, color and resistanceto fracture.

It is a primary object of the invention to provide an improved method offorming jacket crowns overcoming the disadvantages of the ordinarytechniques for the preparation of porcelain jacket crowns.

Another object of the invention is to reduce the time of preparation ofjacket crowns.

Still another object of the invention is to improve the technique offorming jacket crowns so that the technique is within the skill ofnon-specialized workers and therefore not requiring the skill andtraining of dental technicians.

A further object of the invention is to improve the technique of formingjacket crowns so that the correct colors and shades are secured beforestarting work.

Another object of the invention is to provide an improved technique informing jacket crowns so that higher over-all resistance does not dependto a large extent on manipulation or baking.

Another object of the invention is to provide an improved porcelainjacket crown, a portion thereof including a high melting pointporcelain, and the remainder completed with a porcelain fromsubstantially low to middle melting point, together with a compensatingporcelain.

Another object of the invention is to provide a compensating porcelainfor fabricating porcelain jacket crowns including porcelains ofdifferent melting points.

Further objects and advantages will become apparent from the followingdescription in which I have set forth a preferred embodiment of myinvention.

Referring to the drawings:

Fig. la illustrates a vestibular view of a prefabricated partial crownfor a superior incisive;

Figs. 2a and 3a illustrate vestibular views of a prefabricated partialcrown for an inferior premolar and a superior molar, respectively;

Figs. 1b, 2b, and 3b illustrate the same crowns as Figs. la, 2a, and 3a,respectively, viewed from their proximal faces where their prornixalextension as well as the hollow portions may be seen;

Figs. lc, 2c and 3c illustrate the lingual view of the crowns of Figs.la, 2n, and 3a, respectively;

Figs. 4 and 5 illustrate a longitudinal section of matrices or diessuitable for use in the preparation of biscuited porcelain jacket crownsof a superior incisive and an inferior molar, respectively;

Figs. 6 and 7 show the partial prefabricated crowns in place on thematrices or dies, together with a layer of compensating porcelain;

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Figs. 8 and 9 illustrate a later stage in the production of the crowns;and

Figs. 10 and 1l illustrate the incisive and premolar jacket crownfinished and separated from their corresponding matrices or dies.

According to my invention, the new jacket crown technique describedherein overcomes the above-mentioned disadvantages in a simple and rapidway ensuring in advance substantial success as regards shape, color andresistance.

The basic differences between the new technique submitted herein and theones known heretofore are:

1. On the basis of the clinical determinations of a pure gold matrix,instead of a platinum one, is prepared. The advantages of this are alower cost and easier manipulation.

2. A tooth of a high melting point porcelain is selected with aprosthetic purpose (whole set of teeth or partial set, bridges, etc.)choosing the most suitable as regards shape and color. The crown is thenprepared so as to enable the setting thereof on the stump in a correctposition, leaving a space between the prepared tooth and the goldmatrix. In this manner, I obtain a high melting point porcelain facethat will reproduce the interior face of the crown. The possibility ofprefabricated faces embracing one half or two thirds of the crown willmake the technique even faster and more successful and simpler as well.

In this manner, it is then only necessary to finish the crown withporcelain of a lower melting point than that of the face so as not tosubmit this latter to conditions of overmelting which would cause lossof stain and of resistance.

On trying to join the face with the fresh mass of porcelain, which has alower melting point than that of the face, cracks are brought about as aresult of differences in expansion coefficients, preventing the closeunion of the two porcelains, owing to the thickness of the massrequired.

In order to overcome this diiculty, my technique provides for theemployment of granulated porcelain of high melting point and comprisingparticles of various sizes, which is laid between the above-mentionedface and the fresh mass of low melting point porcelain added in order tonish the crown.

With this granulated porcelain substance a regulation of contractiondifferences is obtained, thus ensuring the close union of bothporcelains and, as a result thereof, the resistance of the entire massand consequently that of the jacket is increased, so that in trying tobreak the jacket, a fracture will not occur where the welding caused bythe compensating substance has taken place. Furthermore, if theresistance of the face is increased by the process of additionelaborated above, it is evident that the jacket as a whole is by farmore resistant than those obtained by the known techniques.

Due to my special process for the prefabrication of one half or twothirds of the crowns to be used in jacket crown preparation asillustrated in Figs. ltr-3c, inclusive, my technique will permit aneasier application to all dental pieces and will no longer beexclusively for the anterior teeth as heretofore.

Also, this higher resistance brings about a simplification in theclinical preparation of the tooth; a feature to be taken well intoaccount considering the present dili'lculties.

Referring to Figs. 4-11, inclusive, there are illustrated two instancesof my technique for the production of biscuited porcelain jacket crownsfor a superior incisive and an inferior molar following the disclosureof my process for the preparation of porcelain jacket crowns. The dottedline A indicates the thickness of the $42 or 2/3 prefabricated crown.The space B lying between the 1/ or prefabricated crown and the die isjointly occupied by the low melting point porcelain and the eXtra-tinegranulated compensating porcelain that will act as an eXpansioncompensator or regulator. The reference character C of Figs. 8 and 9indicates the portion of the crown to be nished by the dental Workerwith low melting point porcelain and compensating porcelain and D theboundary therebetween. The reference character E represents the"corresponding portion of the crown prefabricated with high meltingpoint porcelain. The reference character F represents that part of thecrown finished by the dental worker with low melting point porcelain andthe various compensating porcelains to be ultimately used on thedifferent zones of the crown.

Comparison of the techniques Time:

Known technique--longer time--4 to bakings. My technique-shortertime-only 2 bakmgs.

i Manipulation:

Known techniquegreat skill and long training required.

My technique-easy manipulation within the reach of non-specializedworkers.

1 Color:

Known technique-difficult to obtain requiring very often repeatedworking.

My technique-color and shades'secured before starting work.

; Resistance:

It is thus evident that I have disclosed a new process which is readilyadapted for the production of biscuited porcelain jacket crowns forapplication in dental work.

Furthermore, I have also disclosed a high melting point biscuitedporcelain tooth with a shape similar to a half crown or two thirds of acrown to be used on anterior or posterior teeth.

Likewise, I have also disclosed a new ceramic product that might betermed .compensating porcelain basically made of fine particles ofbiscuited porcelain, of a number of shapes and sizes, acting as aregulator or compensator of the various expansion coefficients ofdifferent porcelains thus facilitating the close union of differentporcelains and providing the total mass thereof with a higher resistanceto fracture. This particular feature enables the production of everykind of porcelain crowns or similar works, in far fewer fusions than arerequired when applying previously known techniques and with far betterresults as regards shape, colour or resistance. Furthermore, with mytechnique of selecting 1/2 or 2/3 of prefabricated crowns, I haveovercome the serious problems arising when dental workers strive foraccuracy in jacket crown colour. Prior to my technique, it was necessaryfor manufacturers to supply the market with large and costly porcelainpackages containing a huge assortment of stains and colours to be usedby the dental worker in the production of jacket crowns.

It is therefore possible with my technique to use a much simplerporcelain package which would need to contain only: (1) a few basicporcelain colours of middle or low melting point to be employed infinishing the crown; (2) staining elements of the kind currently used; 3glazing porcelain to suit the porcelains used in the production ofjacket crowns of high and low melting points; and (4) compensatingporcelain (unknown heretofore) to be jointly used with the low or middlemelting point porcelain in the finishing of the porcelain crown.

Although I have shown and described preferred forms of my invention, Icontemplate that various departures may be made therefrom withoutdeparting from the spirit of my invention.

What I claim is:

1. A jacket crown for teeth, comprising a Prefabricated member made fromhigh meltingv point porcelain, and a second member made of amixture-here called compensating porcelainw-consisting of a low meltingpoint porcelain and granules of a high melting point porcelain, saidmembers being joined together by baking.

2. A jacket crown as set forth in claim 1, in which said Prefabricatedmember forms the vestibular parts of the tooth, while said second memberforms the lingual parts of the tooth.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 643,989 Sehr Feb. 20, 1900 1,248,242 Babcock Nov. 27, 19171,671,104 Eberly May 29, 1928 1,794,129 Walsh Feb. 24, 1931 2,314,957Thornton et al Mar. 30, 1943 2,341,908 Lee et al. Feb. 15, 19442,391,106 Safr Dec. 18, 1945 FOREIGN PATENTS Number Country Date 561,526Great Britain May 23, 1944

